In the Reports, only a user with Admin or Report Reviewer Full control privilege is able to see a hidden section.
If you hide a submit, the learner will not see that submit in the Individual Checklist report (if the report is made available for the students).
However, if you hide the entire record, the learner will still see the individual submits within that record even if the entire record is hidden.
If you want to hide the submits from the learners, you need to hide them individually and not only hide the entire record.
Hiding submits and hiding entire record works the same way in score calculation: score of a hidden submit do not count in overall score and if entire record is hidden, scores of all submits (SP, FOn, Learner) within that record will be ignored in score calculation.